Snap action valve mechanism



Nov. 15, 1949 W. HUNGATE SNAP ACTION VALVE MECHANISM Filed April 12, 1946 2 Sheets-Sheet l INVENTOR.

ATTORNEY.

Nov. 15, 1949 HUN ATE 2,488,125

SNAP ACTION VALVE MECHANISM Filed April 12, 1946 2 Sheets-Sheet 2 v giqgwllgllamlwmlllmlmlmllaz1'. 28 W 7Z4ZMOZLAMMNVENTOR 10 Ami M ATTORNEY.

Patented Nov. 15, 1949 SNAP ACTION VALVE MECHANISM William Hungate, Houston, Tex., assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N. J., a corporation of Delaware Application April 12, 1946, Serial No. 661,828

3 Claims. l

The present invention is directed to a mechanism for operating the valves of a steam enlue.

The device of the present invention may be described as a mechanism adapted to be applied to a steam engine provided with a piston operatingin a cylinder, a valve rod, and valves carried by the valve rod for controlling the entry of steam into the cylinder, the mechanism involving a means for storing energy during the major portion of each stroke of the piston and suddenly releasing the energy to move the valve rod as the piston approaches the end of each stroke to change the setting of the valve whereby the direction of flow of steam into the cylinder is reversed. In other words, the device may be described as a snap-acting valve mechanism which is operated by the reciprocating motion of a piston and operates the valve controlling the direction of flow of steam into the cylinder in which the piston reciprocates.

The invention will now be described in conjunction with the drawing, in which Fig. l is in the form of an elevation, partly in section, showing an embodiment of the present invention;

Fig. 2 is a view taken along line IIII of Fig. 7

1; and

Fig. 3 is a view taken along line III-III of Fig. l. g V V In the drawing the principal elements of the device are designated by letters and the remaining portions are designated by reference numerals.

A spring A is mounted in a'tube B which, in turn, is arranged to drive valve C. A linkage D is arranged to supply energy to spring A upon reciprocation of piston rod E. A holding and releasing mechanism F is arranged to hold tube B against movement during the major portion of the stroke of valve rod E and a knock-off arm G is arranged to operate the holding and release mechanism as the piston rod E approaches the end of its stroke, whereby the stored up energy in spring A may be released to drive valve C and reverse the direction of flow of steam into the steam engine.

Considering now the drawing in detail, the body I l of a steam pump defines a steam cylinder having an inner wall I2 in which piston I3 is arranged to reciprocate. Secured to the piston is piston rod E which passes through a suitable packing means comprising a packing gland l5 and a follower 16 mounted on the cylinder head I! of the pump. The body ll of the steam pump defines conventional steam inlet and outlet passages arranged to be controlled by suitable valves; these passages and valves are not shown in detail. A portion of the passages is shown which defines the passage in which valve C is arranged to reciprocate, while a single valve C is shown by way of representing the plurality of valves with which the engine is provided.

The spring A and mounting means therefor, including drivin tube 13, will first be described in detail. A spindle 22 has spaced collars 23 and 24 attached thereto. -Washers 25 and 26 are slidably mounted on spindle 22; these washers each define an annulus with the inner diameter thereof less than the maximum diameter of collars 23 and 2t and a maximum diameter greater than the maximum diameter of the collars. In other words, the collars serve to limit the longitudinal movement of the washers, while at the same time each washer defines a circular shoulder projecting above the adjacent collar. Spring A is mounted on spindle 22 with one end resting against washer 25 and the other end resting against washer 26. Secured to the ends of driving tube B are annulae 21 and 28; the minimum iameter of these annulae are greater than the maximum diameter of collars 23 and 24, whereby the annulae are freely slidable over these collars, but are less than the maximum diameter of washers 2i and 28. Annulus 21 accordingly defines a shoulder which is in contact with the outer surface of shoulder defined by washer 25 and, similarly, annulus 28 defines a shoulder which is in contact with the shoulder defined by washer 26. Annulus 28 is mechanically connected to valve C through links 29 and valve rod 30.

A lug 48 projects upwardly from the upper surface of driving tube B.

From the description of the arrangement of spring A and driving tube B, it will be evident that when the drivin tube is held against longitudinal movement, the movement of spindle 22 to the right will cause Washer 25 to move to the right and compress spring A, while the movement of spindle 22 to the left will cause washer 28 to move to the left and compress spring A.

Piston rod E has a cross-head 3i mounted thereupon. Frame 32 is mounted on body I l of the pump. Affixed to frame 32 is a shaft 33, which serves as a pivot for cross-head arm 34. The lower end of the cross-head arm 34 has aroller 35 secured thereto; the roller 35 fits into the slot defined by cross-head 3i and causes the crosshead arm to oscillate as the piston rod E recipro- 3 cates. The upper end of cross-head arm 34 is bifurcated and is designated as 36.

The projecting end of spindle 22 defines an opening for receiving a transversely extending pin 31. A link 38 has one end attached to pin 3'! and the other end pivoted to the upper end of portion 36 of the cross-head arm, and link 38' similarly has one end attached to pin 31 and the other end pivoted to the upper end of portion 36 of the cross-head arm. It will be seen that, as the cross-head arm oscillates and upper end portions 36 and 36' thereof move to the right, the spindle 22 is moved to the right and when the upper end portions 36 and 36' move to the left, the spindle 22 is similarly moved to the left.

A block 6 is provided with a transverse passage arranged to fit slidingly over shaft 33 and is mounted on the shaft between portions 36 and 36 of cross-head arm 34. A downwardly extending lug is attached to the under side of driving tube B. The upper end of block is provided witha suitable groove 8 for receiving lug 1, and block 6 and lug I are provided with transversely extending passages for receiving a pin 9 whereby the driving tube is secured to block 5 and is free to oscillate about shaft 33.

Frame 32 serves as a mounting means for the holding and release device F. The holding and release mechanism includes a pair of arms 4| and 4| which are pivoted to frame 32 on transversely extending pins 42 and 42. The outer ends of arms 4| and 4| are provided with upwardly extending pins 43 and 43', respectively. A spring 44 has one end attached to pin 43 and the other end attached to pin 43' and is in tension to bias the inner adjacent ends of arms 4| and 4| downwardly. Secured to the adjacent ends of lever arms 4| and 4| are cam rollers 45 and 45', respectively. Arm 4| is adapted to assume a first position in which its longitudinal axis is substantially horizontal and cam roller 45 rests on the upper surface of lug 46, and a second position in which its longitudinal axis is tilted and roller 45 rests on tube B and, similarly,

arm 4| is adapted to assumea first position in which its longitudinal axis is substantially horizontal and cam roller 45' rests on lug 46 and a second position in which its longitudinal axis is tilted and roller 45 rests on tube B. The cam rollers are arranged to cooperate with lug that is to say, when lever arm 4| is in its second position, the roller contacts a side of lug 4G and locks driving tube B against movement to the right and, similarly, when lever arm 4| is in its second position the roller 45 is in contact with a side of lug 40 and locks driving tube B against movement to the left.

Means are arranged for forcing the outer ends of arms 4| and 4| downwardly. A cam roller 46 is mounted on arm 4| adjacent the outer end thereof and a similar cam roller 46 is mounted on arm 4| adjacent the outer end thereof. Knock-off arm G has its lower end defining a journal fitting over shaft 33 whereby it may be oscillated about the shaft and is secured to end portion 33 of cross-head arm 34 by a suitable means, such as pin 4?. Accordingly, as crosshead arm 34 oscillates, knock-off arm G also oscillates.

As the piston rod E moves to the right and approaches the end of the stroke in this direction, knock-off arm G is brought into contact with cam roller 45' and rotates lever arm 4| in a counter-clockwise direction about pin 42 to move it from its second to its first position; this brings cam roller 45 up and releases the driving tube for movement to the left. As the driving tube moves to the left, lever arm 4| moves from its first to its second position; this brings cam roller 45 down and into contact with the side of lug 40. On the return stroke of piston rod E the driving tube is held against movement during the major portion of the stroke by contact of cam roller 45 with lug 40; as the piston E approaches the end of its stroke to the left, knock-off arm G comes in contact with cam roller 46 and moves arm 42 from its second to its first position to release driving tube B, which thereupon moves to the right under the influence of the energy stored in spring A. The movement of the driving tube to the right, in turn, moves valve rode 36 and the valves controlling the inlet and ex haust ports of the steam engine.

The nature and objects of the present invention having been fully described and illustrated, what is claimed as new and useful and is desired to be secured by Letters Patent is:

1. A device adapted for activating the valve rod of a steam engine having a piston and piston rod and valves coverin the inlet and exhaust ports of the engine carried on a valve rod, comprising, in combination, a cylinder having slidable ends carried by the free end of said valve rod in axial alignment therewith, means at either end of the cylinder for preventing outward motion of said slidable ends, a compression spring arranged between said slidable ends, a rod passing through said slidable ends provided with stops to cause one of said slidable ends to move with said rod, means for locking said cylinder in a fixed position during the major portion of the stroke of said piston rod, means carried by said piston rod for causing one of said slidable ends to move in a given direction concurrently with the movement of said piston rod thereby to build up pressure in said spring and means carried by said piston rod for releasing said locking means at a predetermined point near the end of the stroke of said piston rod whereby the built up compression in said spring is applied axially to said valve rod to move said valves to a new position.

2. A device adapted for activating the valve rod of a steam engine having a piston and piston rod and valves covering the inlet and exhaust ports of the enginecarried by a Valve rod, comprising, in combination, a driving tube, a link age connecting the driving tube with the valve rod, a spring mounted in said driving tub-e and arranged to transmit stored up energy to the driving tube in a direction parallel with the motion of the valve rod, an oscillating arm adapted to be pivoted to a base with one end connected to the piston rod of the engine whereby reciprocation of the piston rod causes the arm to oscillate, a linkage between the oscillating arm and the spring to supply energy to the spring upon movement of the piston rod, a first holding arm adapted to be pivoted to the frame of the engine and adapted to lock the driving tube against motion in a first direction during the major portion of the stroke of the piston rod when moving in a first direction and to be released by contact with the oscillating arm at a predetermined point near the end of the stroke of said piston rod, a second arm adaptedto be pivoted to a base and arranged to hold the driving tube against longitudinal motion in a second direction during the major portion of the stroke of the piston rod when the piston rod is moving in a second direction and to be released by contact with the oscillating arm at a predetermined point near the end of the stroke of the piston rod.

3. A device for operating the valves of a steam engine having a piston and piston rod and valves covering the inlet and exhaust ports of the engine carried by a valve rod, comprising, in combination, a driving tube adapted to be mechanically linked to the valve rod for moving the valve rod longitudinally, a lug laterally projecting from said driving tube, an oscillating arm adapted to be pivoted to a base with one end connected to the piston rod of the engine whereby oscillation of the piston rod causes the arm to oscillate a first holding arm adapted to be pivoted to a base and arranged to assume a first position in contact with the lug to prevent the movement of the tube longitudinally in a first direction and a second position releasing the lug for movement of the tube in said first direction, a second holding arm adapted to be pivoted to a base adapted to assume a first position in contact with the lug to prevent movement of the tubelongitudinally in a second direction and to assume a second position releasing the lug for movement of the tube in the second direction, a cam surface carried by the first holding arm arranged to cooperate with said oscillating arm to move the first holding arm from its first to its second position when the piston rod approaches the end of its stroke in a first direction, and a cam surface carried REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 953,993 Forbes Apr. 5, 1910 2,404,315 Rotter et al. July 16, 1946 

